Testing SD cards: I've tested some of my SD cards using h2testw with worrying results. Three of them were SanDisk Extreme rated at 45 MB/s and they tested out at ~31MB/s write speed...

R.G. Loc: Scotland

I've tested some of my SD cards using h2testw with worrying results. Three of them were SanDisk Extreme rated at 45 MB/s and they tested out at ~31MB/s write speed and ~38MB/s read speed, which is probably OK because the indicated speed of 45MB/s refers to peak read speeds.

The worrying bit is when I tested another SanDisk Extreme card with an indicated speed of 90MB/s. It tested out at ~21MB/s write speed and ~28MB/s read speed. That's the one I had in my DSLR because I thought it was the fastest card. I probably paid quite a bit more for that indicated speed increase.

The internet seems to be awash with stories of fake goods. The biggest liabilities seem to be big name brands that are bought online through large third party vendors like Amazon. The annoying thing is that the alternative smaller vendors often charge significantly more for the same products.

johngault007 Loc: Florida Panhandle

R.G. wrote:

I've tested some of my SD cards using h2testw with... (show quote)

You have to consider that these test speeds are conducted in very controlled and optimum environments. The same happens with WIFI standards and equipment testing. So realistically the numbers will be lower due to many factors beyond our control.

But I can see concern with paying considerably extra for a "better" card and it under performs less expensive cards.

R.G. Loc: Scotland

johngault007 wrote:

You have to consider that these test speeds are conducted in very controlled and optimum environments. The same happens with WIFI standards and equipment testing. So realistically the numbers will be lower due to many factors beyond our control.

But I can see concern with paying considerably extra for a "better" card and it under performs less expensive cards.

The three 45MB/s cards were consistently very close. What I would agree with is the suggestion that the stated speeds are just possible maximums that are achieved under ideal conditions (and not in real world conditions).

rgrenaderphoto Loc: Hollywood, CA

R.G. wrote:

I've tested some of my SD cards using h2testw with... (show quote)

Never, ever purchase memory cards via Amazon, their listings are full of fakes and crappy products. Whoever made your SD card was probably the same factory that makes SanDisk's products. Who is to know that an extra 100,000 SD card labels were printed?

I only purchase memory at major retailers like Best Buy or dependable camera stores like Samys, B&H or vendors directly like Delkin.

chase4 Loc: Punta Corona, California

Perhaps this link may help you: https://www.cameramemoryspeed.com

Best, chase

R.G. Loc: Scotland

rgrenaderphoto wrote:

....Whoever made your SD card was probably the same factory that makes SanDisk's products. Who is to know that an extra 100,000 SD card labels were printed?...

I'm left wondering if "Made in China" might be an indicator of questionable authenticity.

R.G. Loc: Scotland

chase4 wrote:

Perhaps this link may help you: https://www.cameramemoryspeed.com

Best, chase

Thanks for the link. I'm not querying the test or its results. I think it's fairly obvious that the card that should have been twice as fast was not as described on the label.

Rongnongno Loc: FL

There are several factors here...

What is the USB port speed? These are not exactly accurate either...

R.G. Loc: Scotland

Rongnongno wrote:

There are several factors here...

What is the USB port speed? These are not exactly accurate either...

I was using a USB 3 card reader. Neither the reader nor the USB port would explain why a card that should have been twice as fast was 2/3 as fast.

Rongnongno Loc: FL

I used the software and discovered something...

If you use a short test the speed of a card is 85mb/s rated at 95mb/s short test (200mb).

I also tested a microdrive with the 200M. The speed was 61mb/s, there is no indication of the rated speed on the card.

R.G. Loc: Scotland

Rongnongno wrote:

I used the software and discovered something...

If you use a short test the speed of a card is 85mb/s rated at 95mb/s short test (200mb).

I also tested a microdrive with the 200M. The speed was 61mb/s, there is no indication of the rated speed on the card.

It's recommended that you test all available space because it'll show up any bad sectors. It takes longer but if the test is completed without any errors you know that the whole drive is OK. It's also recommended that you perform the test on an empty, recently formatted drive.

Longshadow Loc: Audubon, PA, United States

R.G. wrote:

The three 45MB/s cards were consistently very close. What I would agree with is the suggestion that the stated speeds are just possible maximums that are achieved under ideal conditions (and not in real world conditions).

Yup, tested under laboratory conditions with specific equipment.
Outside of the lab, in what applications, who knows.
Just because the chip will accommodate certain speeds, it will only work as fast as the system in which it is used.
(I used to test/qualify ICs.)

Longshadow Loc: Audubon, PA, United States

R.G. wrote:

It's recommended that you test all available space because it'll show up any bad sectors. It takes longer but if the test is completed without any errors you know that the whole drive is OK. It's also recommended that you perform the test on an empty, recently formatted drive.

You do realize that memory chips don't "erase" what is there before writing the new data.
They just write the new data over the old.

BebuLamar

R.G. wrote:

I'm left wondering if "Made in China" might be an indicator of questionable authenticity.

Nope! Most cards are made in China.

User ID

So testing cards seems to be very much like testing lenses, scarcely meaningful.

I go to Bestbuy and simply buy SanDisk Extreme or Extreme Pro interchangeably, 64 or 128 gig depending on file size, at whatever the sale price may be. Then I test it. If it works, it passes the test.

FWIW I notice you didn’t post the speed of your camera, neither rated nor tested. So why do you fret over the test results of your cards ? Most likely they’re faster than your camera anywho.